Some common problems of a turbocharger include oil leaks, excessive noise, smoke, loss of power, overheating, and surging. These problems can be caused by various factors, such as poor lubrication, dirty or contaminated oil, faulty seals or bearings, damaged blades or housings, clogged air filters or intercoolers, or improper tuning or calibration. To solve these problems, you should inspect and repair or replace the faulty parts, clean or flush the oil system, adjust or reset the boost pressure or wastegate settings, or consult with a qualified mechanic.